1. Technical Field
Embodiments described herein are related to analog to digital converters (ADCs), and more particularly to amplifiers included in ADCs.
2. Description of the Related Art
High-speed, high resolution pipelined ADCs employ large sampling capacitance to meet the stringent noise requirements demanded in communication systems like Long Term Evolution (LTE). One type of ADC which may be used in such systems is a multiplying digital to analog converter (MDAC) operational transconductance amplifier (OTA). The MDAC OTA drives large sampling and feedback capacitors, and thus itself is large. The relative distance between the components increases as the size of each increases, which increases parasitic interconnect resistance and capacitance. As sampling rates in the ADCs increase, the settling time of the MDAC increases as well, further exacerbated by the parasitic resistance and capacitance. The relatively large size of the OTA and the sampling/feedback capacitors also results in variations due to process gradients over the semiconductor area occupied by these components, impacting the overall ADC performance as well.